The experimental investigation of copper for superconductors

The connection between microstructure and electrical transport properties o f 99.99% purity copper for Cu-stabilization of superconductors has been inv estigated. Microstructure of copper was studied by optical and transmission electron microscopy. The chemical composition analysis of impurities has b een carried out on base of the laser mass-spectrometry data. The electrical transport properties have been estimated by residual resistance ratio (RRR ). It is shown that the difference in RRR values obtained for the studied s amples are connected to the microstructure features, mainly with the surfac e of grain boundaries and concentration of second phases precipitation. The experimental correlation of RRR and concentration of precipitation (0.01-0 .08 vol%) and oxygen content (0.001-0.003 wt.%) have been obtained. The inf luence of the conduction electron scattering by the different mechanisms on the electrical conductivity has been discussed. The comparison of measured RRR values and theoretically estimated ones was carried out. (C) 2001 Else vier Science B.V. All rights reserved.